Fe中刃型位错上扭折及掺杂体系的电子结构

利用离散变分方法和DMol方法，研究了体心立方Fe中1/2［111］（110）刃型位错上扭折及掺杂（N，O）体系的电子结构.能量（杂质偏聚能及格位能）计算结果表明，杂质元素N，O进入扭折芯区的偏聚趋势，这与位错扭折引起的晶格畸变有关.同时，在杂质元素周围有一些电荷聚集，导致扭折上电荷的不均匀分布，杂质原子得到电子，其周围Fe原子失去电子.由于N原子的2p轨道与近邻Fe原子的3d4s4p轨道之间杂化，使N原子与近邻Fe原子间有较强的相互作用，不利于扭折的迁移，使位错运动受阻，有利于材料强度的提高；而O与最近邻Fe原子之间的相互作用较弱.杂质-扭折复合体的局域效应明显影响体系的电子结构、能量及性能. 关键词： 电子结构 刃型位错 扭折 杂质元素

Electronic structure and doping effect of kink in edge dislocation of body-centred cubic iron

The self-consistent discrete variational method and the DMol method， based on the density functional theory， are employed to study the electronic structure and the doping effect （N，O） of the kink in the 1/2［111］（110） edge dislocation of body-centred cubic Fe. Our calculations of energies （impurity segregation energy and structural energy） show that N and O each have a strong segregation tendency to enter a kink region， which is related to the lattice distortion introduced by the kink. Furthermore， we find that there exist some charge accumulations between impurity and its neighbouring Fe atoms， resulting in unhomogeneous charge distribution in the kink. N and O atoms obtain electrons while the neighbouring Fe atoms lose electrons. It is found that the interactions between impurity N atom and neighbouring Fe atoms are strengthened due to the strong hybridizations between N-p and Fe-3d4s4p states. The migrations of kink and dislocation motion are impeded by N， which may be beneficial to an increase in strength of material. While the interaction between O and its neighbouring Fe atoms is weaker. The localized effect of impurity-kink complex distinctly affects the electronic structure and properties of the system.